The interior ministry said in a statement that "the authorities are investigating the circumstances of the death, which is presumed to have occurred at the hands of a member of the National Police."

It added: "We are going to establish fully what happened, and those responsible will be brought to justice."

Police raided the party offices after activists took refuge there during a night of riots, Alegre said.

The injured included three lawmakers, according to firefighters and an opposition senator. Police said 211 people were arrested, some of them minors.

To chants of "Dictatorship never again!" hundreds of protesters clashed with riot police, who used mounted units and water cannon to disperse them.

Calm was restored around 0400 GMT Saturday. Large numbers of police remained on alert.

Rubber bullets

Cartes's allies in the upper house of the legislature passed the bill on Friday, sidestepping resistance from opponents.
Th

e vote took place in Senate offices as the main assembly hall was occupied by senators from the Liberal Party, opposed to the reforms.

Opposition senator Luis Wagner said those injured included Senate speaker Roberto Acevedo, lawmaker Edgar Ortiz, who was hit in the mouth by a rubber bullet fired by police, and Liberal leader Alegre, who lost to Cartes in the 2013 presidential elections.

Acevedo has challenged the bill in the Supreme Court, arguing it is unconstitutional.

The measure was scheduled to be considered Saturday in the Chamber of Deputies, where the president has a majority.

But after the rioting, the president of the lower house, Hugo Velázquez, announced the vote was postponed, saying he was shocked by the violence.

"I hope that calm and harmony will return," Velázquez said in a televised message.